The present invention relates generally to a method of recording much information in a magnetic recording medium in single operation, and more particularly to a method of transferring recording information to a large-capacity, high-recording density magnetic recording medium.
The quantity of information used with personal computers, etc. are now dramatically increased because of wide use of digital images, etc. With an increasing amount of information, there are now demanded mass-storage magnetic recording media that cost less and have ever-shorter write and read time.
High-density recording media such as hard disks and a high-density floppy disk type of magnetic recording media have an information recording area provided with tracks narrower than those used with ordinary floppy disks. To precisely scan narrow track widths with a magnetic head thereby recording and reading signals with high S/N ratios, precise scanning must be effected using tracking servo technology.
For this reason, mass-storage magnetic recording media such as hard disks and removal types of magnetic recording media represented by ZIP (Iomega Co., Ltd.) are currently subjected to the so-called preformatting wherein tracking servo signals, address information signals, read clock signals, etc. are preformatted in one track at a certain interval.
The magnetic head reads these preformatted signals to make correction for its own position, so that it can run over the tracks.
To fabricate a current preformat, a disk is recorded one by one and track by track, using a dedicated servo recorder. The servo recorder is expensive and long is needed for preformatting, resulting in an increased production time. This has some influences on production costs.
For this reason, a magnetic transfer system has been proposed instead of the track-by-track preformatting system. For instance, some transfer techniques are introduced in JP-A""s 63-183623, 10-40544 and 10-269566. However, these publications say nothing about practical conditions for magnetic fields applied for magnetic transfer and practical means for generating such magnetic fields.
To provide a solution to such prior art problems, for instance, JP-A""s 63-183623 and 10-40544 disclose a recording method. According to this method, a substrate is provided on its surface with a pit-and-projection configuration corresponding to information signals. Then, a ferromagnetic thin film is formed on the surface of at least the projection portion of the pit-and-projection configuration to form a magnetic transfer master carrier. While the surface of the master carrier is brought in contact with the surface of a sheet or disk form of magnetic recording medium having a ferromagnetic thin film or ferromagnetic powder coating layer, the ferromagnetic material forming the surface of the projection portion i s energized by the application of an a.c. bias magnetic field or d.c. magnetic field, thereby recording a magnetization pattern corresponding to the pit-and-projection form on the magnetic recording medium.
In the aforesaid method, the surface of the projection portion of the master carrier is brought in close contact with the magnetic recording medium to be preformatted, i.e., a slave medium. At thee same time, the ferromagnetic material forming the projection portion is energized by transfer to form a given format on the slave medium. Thus, this method is characterized in that static recording is feasible without any relative displacement of the slave medium with respect to the magnetic transfer master carrier and so precise preformat recording is feasible. In addition, this method is characterized in that the time needed for recording is very short. Here it is noted that the problems with the aforesaid recording method using a magnetic head are that the recording time of a few minutes to a few tens of minutes is usually needed and the time needed for recording increases further proportional to recording capacity. With the magnetic transfer method, however, it is possible to finish transfer within 1 second irrespective of recording capacity and recording density.
Preformatting pattern transfer from the magnetic transfer master carrier is here explained with reference to FIGS. 1(A) and 1(B). FIG. 1(A) is a plane view in schematic form illustrating a magnetic layer surface of the magnetic transfer master carrier, and FIG. 1(B) is a sectional view illustrative of one transfer process.
A magnetic transfer master carrier 1 is provided at a given track area with a preformat area 2 having a pattern comprising the tracking serve signals and address signals to be transferred, and a data area 3. While the magnetic transfer master carrier 1 is brought in close contact with a slave medium 4, a transfer external magnetic field 6 is applied in a track direction 5, thereby transfer preformat information on the slave medium side in the form of recording information 7. Thus, the slave medium can be fabricated with high efficiency.
When transfer is carried out by such a method, however, it is found that the quality of some information signals often becomes worse with inaccurate servo operation.
An object of the present invention is therefore to provide a stable transfer method and system which can prevent inaccurate servo operation of a slave medium fabricated by a preformat pattern transfer process where while a magnetic transfer master carrier and a slave medium are brought in close contact with each other, an external magnetic field is applied to the salve medium.